1. Field of the Invention
The present invention relates to a container inspecting apparatus for inspecting small cylindrical containers, which may be empty or filled, for defects on their entire external surface, and more particularly to a container inspecting apparatus for inspecting frozen dry vials.
2. Description of the Prior Art
There have been proposed various container inspecting apparatus for inspecting transparent small cylindrical containers such as vials, ampules, or the like. For example, Japanese laid-open patent publications Nos. 1-291110 and 64-38640, respectively disclose a container inspecting apparatus, in which a vial is intermittently fed from a conveyor to a vial gripper, then intermittently fed to an inspecting position by the vial gripper, and intermittently discharged to the conveyor after being inspected in the inspecting position.
The vial gripper comprises a rotary disk for contacting a side of the vial near its bottom, a pair of rollers opposing the rotary disk for contacting the side of the vial near its bottom, and a support plate for supporting the bottom of the vial. The rollers are interconnected by a spring for holding the vial. The support plate has an elongated hole for viewing the bottom of the vial therethrough with a camera. In the inspecting position, the vial is held at rest against the feeding movement, rotated about its own axis by the rotary disk, and viewed at its top, side, and bottom during rotation.
However, since the vial is intermittently supplied to and discharged from the vial gripper, the vial movement is relatively unstable. The container inspecting apparatus has a plurality of vial grippers which start and stop moving at the same time. Therefore, the container inspecting apparatus vibrates during operation, and its operating speed cannot be increased.
Another problem of the vial grippers is that inasmuch as the rotary disk and the rollers contact the sides of the vial, an imaging system for imaging the vial with transmitted light is comparatively complex in structure.
Japanese laid-open utility model publications Nos. 3-36948, 3-36949, 3-36950 and Japanese laid-open patent publication No. 1-152347 also disclose a container inspecting apparatus, respectively. In the disclosed container inspecting apparatus, vials are successively supplied from a conveyor to a vial gripper, then successively supplied to inspecting positions by the vial gripper, and successively discharged to the conveyor after being inspected in the inspecting position. Each vial is not stopped in the inspecting position, and for inspecting the entire circumferential wall of the vial, it is rotated about its own axis successively through certain angles while it is being transported.
The vial is gripped by a vacuum pad having a semicircular horizontal cross section which is held against a side surface of the vial. The vial is rotated about its own axis by a rotating roller or belt that is placed in abutment against the side of the vial.
The vial is viewed by successively rotating it through the angles until the full circumferential wall of the vial is imaged. Therefore, the conventional container inspecting apparatus requires a plurality of cameras for imaging a certain region of the vial, and hence are relatively large in size. Light that would be transmitted through the vial cannot be used to inspect the vial because about half of the entire circumferential wall of the vial is concealed by the pad held against the vial in the vial gripper.